brew/Library/Homebrew/dev-cmd/cat.rb

# typed: true
# frozen_string_literal: true

require "cli/parser"

module Homebrew
  sig { returns(CLI::Parser) }
  def self.cat_args
    Homebrew::CLI::Parser.new do
      description <<~EOS
        Display the source of a <formula> or <cask>.
      EOS

      switch "--formula", "--formulae",
             description: "Treat all named arguments as formulae."
      switch "--cask", "--casks",
             description: "Treat all named arguments as casks."

      conflicts "--formula", "--cask"

      named_args [:formula, :cask], min: 1, without_api: true
    end
  end

  def self.cat
    args = cat_args.parse

    cd HOMEBREW_REPOSITORY do
      pager = if Homebrew::EnvConfig.bat?
        ENV["BAT_CONFIG_PATH"] = Homebrew::EnvConfig.bat_config_path
        ENV["BAT_THEME"] = Homebrew::EnvConfig.bat_theme
        ensure_formula_installed!(
          "bat",
          reason:           "displaying <formula>/<cask> source",
          # The user might want to capture the output of `brew cat ...`
          # Redirect stdout to stderr
          output_to_stderr: true,
        ).opt_bin/"bat"
      else
        "cat"
      end

      args.named.to_paths.each do |path|
        next path if path.exist?

        path = path.basename(".rb") if args.cask?

        ofail "#{path}'s source doesn't exist on disk."
      end

      if Homebrew.failed?
        $stderr.puts "The name may be wrong, or the tap hasn't been tapped. Instead try:"
        treat_as = "--cask " if args.cask?
        treat_as = "--formula " if args.formula?
        $stderr.puts "  brew info --github #{treat_as}#{args.named.join(" ")}"
        return
      end

      safe_system pager, *args.named.to_paths
    end
  end
end